Electrical connector



June 23, 1959 F. R. BRERETON ELECTRICAL CONNECTOR 3 Sheets-Sheet 1 Filed Aug. 14, 1957 E .|:l| I B 5, 08 n 9 3 a so 19:? mm 7 mm n QN 2 9h :8 8 om sfiw m .5. 8 m 3 INVENTOR. FREDERICK R. BRERETON BY mld gz AGENT June 23, 1959 v F. R. BRERETON 2,892,173

ELECTRICAL CONNECTOR Filed Aug 14, 1957 3 Sheets-Sheet 2 ll l3 p. as S 4039 I INVENT OR. FREDERICK R. BRERETON AGENT June 23, 1959 F. R. BRERETON 2,892,173

ELECTRICAL CONNECTOR Filed Aug. 14, 1957 s SheetsSheet a VENTOR. FREDERICK BRERETON AGENT States Patent ELECTRICAL CONNECTOR Frederick R. Brereton, Sierra Madre, Califl, assignor to r I North American Aviation, Inc.

This invention relates to electrical connectors and more particularly to connectors for use at high temperatures. More particularly it relates to connectors which can be used at high temperatures and still be pressure tight and sealed against moisture.

No particular problem exists in providing an electrical connector to be used at room temperature or elevated temperatures up to around 400 F. Rubber-like inserts in which the conducting elements are mounted have been used to provide a moisture seal such as is suggested in US. Patent No. 2,731,610. These rubber-like inserts also have been used in order to allow the electrical connectors to vary their position to compensate for the manufacturing tolerance. However, rubber or like resilient material breaks down below 500 F. and is, unusable for a power connector at 1000 F. The present invention provides a connector which is able to use a non-resilient insulating insert which has a thermal coeflicient of expansion approximately the same as a metal shell which is provided for the connector. Thereby, as the temperature is increased and the shell expands, the insert expands along with the shell and no passage forms between the insert and shell through which air or moisture may pass.

Another major problem is to keep moisture away from the wire terminals within the connector in order that a conducting path will not form between various conductors in the connector. In low temperature environment this could be done by providing a rubber-like materialat the point where the wires enter the connector; however, since no rubber materials are available which will stand temperatures up to 1000 degrees, to date no suitable connector for such high temperatures has been suggested or is available. The subject connector provides a means of using materials which will stand the high temperatures and form the moisture seal to insure long operation.

Therefore, an object of this invention is to provide an electrical power connector suitable for high temperature use.

Another object of this invention is to provide an electrical high temperature power connector which is capableof sustaining air pressure while operating at a high temperature.

A further object of this invention is to provide a high temperature electrical power connector which is capable of operating in a humid area without allowing moisture to leak into the wire terminal area.

Other and further objects of this invention will become apparent in the detailed description below wherein:

Fig. 1 shows an enlarged cross-sectional view of a portion of the connector;

Fig. 2 shows an end view of the connector with the screw-in collar removed;

Fig. 3 shows a cross-sectional view of a modification of the wire terminal assembly which is used with the connector;

' Fig. 4 shows another modification of the wire terminal assembly which is used with the connector;

And Fig. 5 shows another wire terminal assembly modification which is used with the connector.

A simple straight power connector is shown and described but it should be understood that the connector could be made into a wall-mounted connector by simply providing a flange for wall-mounting on one of the shells. Also, the connector couldbe constructed with the lead wires on one end of the connector coming out at some angle with the lead wireson the other end by, for instance, designing the portion of the connector with the sockets in it so as to turn at some desired angle.

As shown in Fig. 1, shell means are provided to form a hollow connector body. These shell means include a first shell member 11 and a second shell member 12 which are made of stainless steel and capable of with standing the high operational temperatures. Insulating insert 13 is molded into shell member 11 by any of the methods known in the art such as transfer molding. Transfer molding includes heating the part mold and then forcing the insert in under pressure. Insulating insert 14 is molded into shell member 12 in a similar manner. These insulating inserts are made of a ceramoplastic composition of high-temperature electrical glass and synthetic mica or glass and mica combined under heat and pressure. All of these are capable of withstanding the temperatures involved. This ceramoplastic insulative insert has a coefficient of thermal expansion ipractically the same as stainless steel and, therefore, though the temperature is increased, the'shell members 11 and 12 will not expand away from the insulating inserts 13 and 14 and form a passage for air or gas to leak through the connectors.

Insulating insert 13 is provided with a series of socket members 15 molded therein to form the basic portion of the conducting elements through the connector. Each of these socket members 15 are provided with a socket at one end thereof which is adapted to receive a corresponding pin that is mounted in the second shell member. In order to assure better electrical contact the socket is tapered inwardly or towards the center of the connector. That is, the cross-sectional area of the socket becomes smaller at the end nearer the center of the connector. Also, the socket is provided with four narrow longitudinal slots 10 to allow the socket walls 17 to be moved outwardly by the action of the pin, thus making the electrical contact area spring loaded. Since the insulating insert 13 is made of a non-resilient material the recess 18 is provided in the area around the socket portion 16. Thereby, the socket portion of the socket member may be displaced laterally in order to allow for any manufacturing tolerances between the pins and the socket portions.

A series of pin members 19 are provided in the insert 14. These pin members 19 are provided with pins 20 at one end thereof which have a tapered surface 21 in order to cooperate with the inwardly tapering surface 17 of the sockets and obtain a maximum electrical contact area between the pin 20 and the socket 16. In this relation, broadly speaking, the socket member 15 and pin member 19 provide an elongated electrical conducting means through the insulation means 13 and 14.

At the end of the socket members 15 opposite the sockets 16 bore portions 22 are provided in order to receive the series of wire terminal assemblies. These bore portions are provided with an inwardly tapering surface 23. In this modification four longitudinal slots 9 are pro vided in the socket member 15 around the bore portion 22. Wire terminal 24 is provided with a cylindrical interior and is adapted to receive the end of wire 25 which is connected to some power source or other electrical apparatus. In final assembly the wire terminal 24 is welded to the wire 25 by any one of the processes known iiithe art. Wire terminal 24 is provided with an inwardly tapering surface which has a slightly greater taper than the inwardly tapering surface 23 of the bore portion 22. Thereby maximum electrical contact is obtained when the wire terminal is forced inwardly in the bore portion as the slots 9 allow the tapered surface 23 tomove outwardly slightly providing a spring loaded electrical contact. Similar to the recess provided around the socket, recess 27 is provided in the insert in the area of the bore portion 22. This recess 27 plus the slots 9 allow a slight lateral movement of the bore portion of the socket member in order to compensate for manu-' facturing imperfections.

The insulation'28 on the wire 25 is cleaned off of the wire to a point outside of theconnector. This is because the wires which are presently available on the market are not provided with insulation which is adapted tdusein high temperature conditions without failure of the insulation at the connector wire terminal. For this reason, connector wire terminals which depend on maintaining a; seal against the insulation of the wire are unusable at the high temperatures required. Therefore, an insulating sleeve in the form of ceramic tube 29 is provided as shown and is adapted to receive the wire 25 in final assembly of the connector. A wire cap 30 is provided at the outward end of the ceramic tube. The wire cap 30 has an inwardly facing flange 31 which is soldered to the ceramic tube 29. The inside diameter of the inwardly facing flange 31 is larger than the external diameter of wire 25 in order that the flange will not touch the wire and become hot thereby endangering the personnel working with the connector. The wire cap 30 is also provided with a circular flange at its outward end which is sealed to the insulation 28 of thewire by means such as swaging. Wire collar 32, provided around each ceramic tube 29, also encircles wire 25 when the wire is inserted in wire terminal 24-, and is provided with an outwardly tapering external surface 33 which cooperates with the tapered bores in back plate 35 as described below. As used in this specification and claims, outwardly tapering means that the cross-sectional area of the collar becomes smallest at the end furtherest from the center of the connector. The wire collar 32 is provided with an external flange 34 at its inward. end which is adapted to receive pressure from connector end sealing means such as back plate 35,as the back plate is forced inward towards the center of the connector by a means to be later described.

The back plate 35 is provided with a series of bores coinciding with the position of the wire collars 32. These bores each have a peripheral surface 36 which is outwardly tapering or tapering away from the center of the connector in order to match the outwardly tapering surface 33 of each wire collar 32. The largest diameter of each bore is slightly smaller than the largest diameter of the surface 33 of wire collar 32. Thereby, as the back plate is moved towards the center of the connector it not only forces the wire collar 32 towards the center through engagement of the flange 34 and the tapered surface 33, but it also shrinks the wire collar 32 onto the external surface of the ceramic tube 29 by action of the tapered surfaces 36 and 33. This shrinking; action makes a compression-fit pressure and moisture seal between the back plate, the wire collar 32 and the ceramic tube 29 as the tube is non-resilient. Insulating washer 37 is provided on the inward side of each of the wire collars 32, and is provided with a series of bores through which the ceramic tubes 29 may fit.

In order to force the end assembly of the connector into operative position a means must be provided toforce the back plate 35 towards the center of the connector and through. this action the other parts of thewire assembly will be forced into sealing relation. In. the preferred modification shown this means is in the form of screw-in collar 38 which is threaded into the outward end of shell member 12 and is adapted to abut back plate 35 to force it towards the center of the connector.

With this configuration the only possible leakage path would occur if the insulation 28 failed allowing moisture to pass between the wire cap 30 and the insulation 28 and then between the ceramic tube 29 and the wire 25. However, this is a relatively long leakage path and also the moisture is stopped by the sealing relation of the ceramic tube 29, asoft metal washer 39 (described below), and the wire terminal 24 in which wire 25 is welded.

Since all of the wire terminals 24 and the wire gripping collars 32 are not of exactly the same dimensions, a soft metal washer 39 is provided adjacent each external flange 40 on each wire terminal 24. This Washer 39 may be made out of any suitable metal such as copper or brassso that it can be compressed as needed to allow for manufacturing tolerances.

Inorder to stop moisture or gas from leaking past the outside of the back plate 35 into the connector, an as: bestos filled metal washer 41, is provided in the insert 13 and is adapted to engage the back plate near the periphery of the back plate 35 in sealing relation. Thereby, as screw-incollar 38 is threaded into the shell member. 1 1. the back plate 35 seals against the' asbestos filledmetal washer 41 and the insert 13 while also sealing. itself against the wire collar 32 and forcing said wire gripping collar into sealing relation with the ceramic tube Simultaneously, the back plate 35 forces the insulating washer 37 against the soft metal washer 39 and thereby forces the wireterminal 24 into electrical contact with the bore portion 22. of socket member 15. With assembly the end ofthe connector is pressure andmoisg turetight even during, high temperature operation.

Theoutward end of the pin member 19 is constructed similar to the outward end of the socket members 15. Here bore portions 42 are provided and have an inwardly tapering surface 43. Wire terminals 44 fit into, the bore portion 42 and are adapted to receive wire 45 as shown, The wire terminal 44 is welded to the wire 45in any suit able manrrer known in the art. The wire terminal .44 is also provided with an inwardly tapering surface 4Q which has a slightly greater taper than inwardly tapering surface 43 of the bore portion 42 as with the above men; tioned bore portion 22. Four slots 8 are provided in the pinmember 19 around the bore portion 42 which allow the bore portion to be expanded by the surface 46 providing. a spring loaded electrical contact. Insert recess 47 is provided in the area around the bore portion of the pin member 19in order to allow the bore portiorrtobe moved laterallv'as needed to compensate for manufactur; ing imperfections.

As witl wire 25 the insulation 48 around the wi re 45. is cleaned off back to a point outside the connector. ceramic tube 49 is provided juxtaposed the wire terminal 44, and similar to the wire terminal is adapted to receive the wire 45 as shown. A wire cap 50 is provided for. each ceramic tube 49 and is soldered to the tube at the; inwardly facing flange 51 in the same manner as wire cap 40'. The wire'cap 50 also has an outwardly extending cir cular flaugewhich is swaged into the insulation 48 of the wire in order to seal against moisture. Wire collar 52- is mounted encircling the wire 45 around the ceramie tube 49 and is provided with an outwardly tapering external surface 53 andalso anexternalfiange 54 at its inward end. Connector end sealing means such asbaclefplate, 55 is. mounted adjacent the outward side-of the flange: 54" of the wire gripping collar and is. provided with a'series ofbores coincident to the location of the wire terminal assemblies. These bores are provided with outwardly,

tapering peripheral surfaces 56 which mate with.,the

tapered surfaces 53;. of fthe wire collars 52 inthe same manner as surfaces 36 matewith surfa'ces 33. Insulat;

ing washer 57 is mounted at the inward side of the respective external flanges 54' and is provided with a series of holes to receive the ceramic tubes 49.

Similar to theopposite end of theconnector, means are provided for forcing thewire terminal assemblies to gether. In the modification shown, a screw-in collar 58 is .threadedinto shell member 12 forcing back plate 55 towards the center of the connector. The peripheral surfaces 56 of the tapered holesin the back plate cooperate with the tapered surface 53 of the wire collar 52 thereby forming a seal between the two tapered surfaces and also forcing the wire gripping collar into sealing relation with the ceramic tube 49. The back plate-55 also engages the external flange 54 of the wire gripping collar forcing it and the insulating washer 57 against the soft metal washer 59 which is provided at the outside of flange 60 on wire gripping terminal 44. As with soft metal washer 39, soft metal washer 59 is provided in order to allow for imperfection in the size and fit of the wire gripping collars 56 and the wire terminals 44. Asbestos filled washer 61 is mounted in the outward end of insert 13 and mates with the back plate 55 near the periphery of said plate thereby a moisture and pressure seal is formed between the back plate and the insulating insert 14. As shown, in order to assure proper alignment of the back plates 35 and 55, keys 63 are provided in shell 11 and in'shell12 which mate with the key-Ways 64 which are provided in back plates 35 and 55 respectively. Fig. 2 shows an end-view of a connector with four wires; however, the present invention could be used with any number of wires in the connector.

Fig. 3 shows another modification of the wire terminal assembly in which the shank of the wire collar 65 is longer. than the shank of the wire collar in the other modification. Similar to the wire collar previously described, r

outwardly tapering external surface 66 is provided to mate with an outwardly tapering peripheral surface 36 of the boresfin the :back plate 35. The wire collar is also provided with the external flange 67 to transmit pressure from the back plate 35 to the insulating washer 37 similar to the external flange 34 in the previously described modification. The collar 65 is also provided with a circular flange portion 68 at its outward end which, when the Wire 25 is inserted in the terminal 24, is swaged into the insulation 28 as shown in order to provide a moisture seal. As described in the other modification, the screwin collar 38 forces the back plate 35 towards the center of the connector and the outwardly tapering peripheral surface 36 of the bores in the back plate engage the tapered surface 66 of the wire collar 65 swaging it against the ceramic tube 29 forming a seal between the back plate, the wire gripping collar and the ceramic tube.

' Fig. 4 shows another modification of the wire terminal assembly for use in connection with anodized aluminum electrical wires. As is known in the art, aluminum may be anodized to form a thin insulating layer of aluminum oxide on its surface which, although very thin, has high insulation properties and will not be decomposed at temperatures below the melting point of the aluminum. In this modification the anodized aluminum coating 70 has been cleaned off of the wire in the area 71 as shown. Ceramic tubes are not needed since anodized aluminum insulation is of a constant high quality and provides a non-resilient insulation member against which the wire collar 72 may be swaged to provide a high temperature seal. Therefore, wire collar 72 is mounted on the outside of insulating washer 37 juxtaposed the wire terminal 24 encircling this non-resilient insulated portion. The wire collar 72 is provided with the outwardly tapering external surface 73 which will cooperate with the outwardly tapering peripheral surface 36 of the bores provided in the back plate 35. The wire collar 72 is also provided with an external flange 74 to transmit the force of the back plate 35 to the insulating washer 37 as the screw-in collar 38 is threaded into the shell 11.

Fig. 5 shows another modification of the wire terminal assembly which is used in more severe conditions. In the other modifications a seal between the back plate 35 and the Wire collars is obtained through cooperation of the tapered surfaces. The wire cap 30 or the swaged end circle flange portion 68 forming a seal between the wire collar and the insulation 28. In extreme conditions wire insulation which is presently available is unpredictable especially when subjected to high temperatures in a fluid such as jet engine fuels; therefore, the seal between the wire insulation 28 and the wire collar might fail due to the failure of the insulation. Because of this, the wire collar 86 is not only provided with an external outwardly tapering surface but its internal surface 87 is also outwardly tapering instead of being cylindrical as in the other modifications. As in the other modifications, the wire collar 86 is provided with an external flange 88 at its inward end to receive the sealing pressure of back plate 35 and is swaged into insulation 28 at its circular flange portion 91 at its outer end. Tapered ceramic tube 89 is mounted within the wire collar 86 and is provided with an external outwardly tapering surface which cooperates with the internal tapered surface of the collar 86. The internal surface of ceramic tube 89 is also outwardly v tapering and cooperates with the .external outwardly tapering surface of wire gripping sleeve 90. The internal sur face of; the sleeve 90 is identical to and normally is slightly larger than the outside diameter of wire 25. With this relationship, as back plate 35 is forced inwardly by action of screw-in collar 38, the tapered peripheral surface 36 of the bore in the back plate 35 cooperates with the external surface of wire collar 86 forming a seal while forcing the collar inward towards the center of the connector. This inward motion forces the internal tapered surface 87 into sealing relation with the external surface of tapered ceramic tube 89, while forcing the internal surface of the ceramic tube into sealing relation with the wire gripping sleeve 90. The cooperation of the internal surface of the ceramic tube and the tapered external surface of sleeve 90 shrinks the sleeve onto the wire in sealing relationship. Thereby, a perfect seal is obtained at the wire terminal no matter how unreliable the insulation 28 of the wire is and there is no danger of personnel working with the connector being electrocuted by touching the wire collar 86.

Referring to Fig. l, nut 75 is provided on the threaded portion 76 of the shell member 12. This nut is provided with an inwardly facing flange 77 which cooperates with the external flange 78 on the shell member 11 to hold the shell members together. Asbestos filled metal washer 79 is provided on the opposite side of external flange 78 to form a moisture seal between the two shell members. Shell member 11 is also provided with a cylindrical portion 80 which extends into the cylindrical cavity 81 between the shell member 12 and the insert 14 in order to provide maximum stability between the two shell members. It can also be seen that should any moisture leak past the metal washer 79 it would have to move along an extremely long path before it could get into the area of the pins 20 and the sockets 16. A metal jacking ring 82 is provided around the external surface of shell member 11; thereby, as nut 75 is backed off of the threads 76 the inwardly facing flange 77 will engage the jacking ring 82 and further backing of the nut 75 will force the shell members 11 and 12 apart.

It should be appreciated that the invention is applicable to any apparatus for providing an electrical connector which is suitable for high temperature use while remaining pressure and moisture tight and that, although only a few forms of the invention have been shown and described, it will be apparent to those skilled in the art that the invention is not so limited but that various modifications may be made therein without deviating from the spirit of the invention or the scope of the appended claims.

I'claim:

I. In an electrical connector, a connectorbody, an electrically conducting'rnembermounted therein, a wire ternri'nar assembly mounted abutting one portion of said conductin'g member, said wire terminal assembly includinga wire tenninal' contacting said conducting member, saidwire-terminal adapted to receive an electrical wire in electricallyconducting relation, a wire collar outwardly juxtaposed to said Wire terminal adapted to encircle the Wireinserted in said wire terminal, said wire collar provided with an outwardly tapering external surface, and insulatingmeans located within and contacting the wire collar and adapted to contact the wire; and connector end sealing means encircling said wire collar for sealing said connector body with said wire terminal assembly, said sealing means provided with at least one bore having an outwardly tapering peripheral surface engaging the externalsurface of the wire collar in compression-fit relation, and means forcing said sealing means towards the center of the connector, whereby a seal is formed betweensaid body, sealing means, collar means and insulation means.

2. The invention as claimed in claim 1 in which said insulation means is the anodized portion of an anodized aluminum electrical wire inserted in said wire terminal through said collar means.

3-. The invention as claimed in claim 1 in which said insulation means is a ceramic sleeve and is provided with a wire' cap mounted at the outward end of said sleeve haying a circular flange extending outwardly which is adapted to be sealed to the insulation of a wire inserted in, said sleeve.

4. In an electrical connector, an outershell forming a hollow connector body, an insulatinginsert within said shell having an electrically conducting member mounted therein, a Wire terminal assembly mounted abutting at least one end of said conducting member, said wire terminal' assembly including: a wire terminal abutting said conducting member and adapted to receive an electrical wire in electrically conducting relation, wire collar means juxtaposed to each said wire terminal adapted to encircle a,wire inserted in said wire terminal, said Wire collar means provided with an outwardly tapering external surface, and insulating means located within the wire collar means having an external surface engaging the interior surface of the wire collar means in sealing relation; connector end sealing means encircling each of said wire collar means for sealing said shell with each of said wire terminal assembly, said sealing means provided with at least one bore having an outwardly tapering peripheral surface engaging the external surface of the wire collar means in compression-fit relation, and means to force said sealing means towards the center of the connector whereby a seal is formed between said shell, sealing means, collar means and insulation means.

'5. In anelectrical connector, a hollow connector body, an insulating insert within said body having an electrically conducting member mounted therein, a wire terminal assembly mounted abutting said conducting member, said wire terminal assembly including: a wire terminal contacting said conducting member and adapted to receive an electrical wire in electrically conducting relation, wire collar means juxtaposedto said wire terminal adapted to 'encircle a wire inserted in said Wire terminal, said wire collar means provided with an outwardlytapering external surface, and an insulating sleeve located within said .wire collar means adapted to encirclea Wire inserted in the 'wire terminal and having an external surface at least partially mating with said wire collar means inlsealing relation, said sleeve being provided with a wireicapjmounted outwardly at theend of. said sleeve away from the wireterrninal, saidv wirefcap rbeing pro vided...with. a. circularlfiange extending outwardly adapted to be sealed to the insulation of?! wire inserted into the wire terminal; and back plate sealing means encircling said wire collar means for sealing saidshell with said; wire terminal" assembly, said sealing means provide with at least one bore having an outwardly tapering peripheral surface engaging the external surface of the wire collar means, in compression-fit relation.

6, In' an electrical connector, shell meansforming aholl ow connector body, an elongated electrically conducting member mounted therein, a wire terminal asg sembly'mounted: at either end of said conducting means, each ofsaid wire terminal assemblies including: a wire terminal contacting said conducting member adapted to receive an electrical wire in electrically conducting relation, a wire collar juxtaposed to said wire terminal outwardly away from the connector body and adapted to encircle arwire insertedin said wire terminal, said wire collar provided with an outwardly tapering external surface, said wire collar provided with a circular flange at its outward end adapted to be sealed to the insulation of a wire inserted into the wire terminal, and an insulating sleeve located within said wire collar having an external surface at least partially mating with said wire collar means; and back plate sealing means encircling each of said wire collars respectively for sealing said shell with, each wire collar, said sealing means provided with atleast one bore having an outwardly tapering peripheral surface engaging the external surface of the wire collar means in compression-fit relation, whereby said collar is shrunk onto-said insulative sleeve.

7. In an electrical connector, a shell forming a hollow connector body and having an elongated electrically conductingmember mounted therein, a wire terminal assembly mounted abutting said conducting member, said wire terminal assembly including: a wire terminalcom tacting said conducting member adapted to receive an electrical wire in electrically conducting relation, a wire collar juxtaposed to said wire terminal, said wire collar provided with outwardly tapering internal and external surfaces, non-resilient insulating means located within said wire collar having a tapered external surface at least partially mating with the internal surface of said wirecollar and having an outwardly tapering internal surface, and an internal wire gripping sleeve located within said non-resilient insulating means adapted to grip a wire inserted in said wire terminal, said wire gripping sleeve having an external tapered surface engaging the internal tapered surface of said non-resilient insulating means, in compression-fit relation; connector end sealing means encircling said wire. collar for sealing said shell. withsaid wire terminal assembly, said sealing means provided with at least onebore having an outwardly tapering peripheral surface engaging said external surface of said. wirecollar means in compression-fit relation, and means to force said connector end sealing means towards the center of the connector thereby forcing said peripheral surface, said Wire collar, said insulation-means, and said internal wire gripping sleeve into said relation.

8. An electrical connector having an outer shell, an internal electrically conductive insert extending therein, an electrically insulative insert between said shell and said conductive insert, an electrically conductive bare. wire terminal abutting and extending co-axially with said. conductive insert and adapted to receive a stripped end of an insertable electrical wire, a cylindrical insulative sleeve surrounding said stripped portion of wire and abutting said terminal cap at an end thereof opposite said conductive insert, a collar surrounding said sleeve and having an externally tapered portion, a backplate s11 r rounding said collar and being substantially coextensive. in cross-section with the end cross-section of said insert, said plate having an. internal bore tapered to engage the tapered surface of said collar, and means to force said back plate against said collar and said sleeve to seal said insertable wire.

9. In an electrical connector, a shell member, an in sulation insert mounted in said shell, an electrically conducting member in said insert having an inwardly tapering bore portion, said insulating insert ibeing recessed away from said conducting member in the area of said bore portion, a wire terminal in said bore and having an inwardly tapering external surface and being provided with an external flange at its outward end, said terminal having a bore adapted to receive an electrical wire, an insulating washer juxtaposed outwardly of the Wire terminal, a wire collar on the outward side of said insulating washer having an outwardly tapering external surface juxtapositioned to said wire terminal, a circular insulating means having an internal surface of substantially identical shape as the conducting portion of a wire inserted in said terminal, said insulation means located within said wire collar, a back plate surrounding said wire collar and having a bore therethrough with an References Cited in the file of this patent UNITED STATES PATENTS Weinhauer Feb. 23, 1909 Thacker Ian. 17, 1956 

